Technical Abstract:
Precision agriculture has mostly emphasized variable-rate nutrients, seeding, and pesticide application. At several research sites, variable-rate irrigation equipment has been developed to explore the potential for managing irrigation spatially. The modifications to commercial machines are relatively straightforward, but costly. Economic analyses have not been positive at current grain price: water cost ratios. However, with increased attention to conservation of water during drought or with increased contention for environmental, recreational, municipal, and industry use, conclusions regarding profitability may change. Regulatory constraints may shift decisions about variable-rate irrigation as well. A 3-year experiment using a site-specific center pivot explored spatially varying irrigation production functions for corn. These equations allow further exploration of the grain yield at maximum yield and at maximum profit. In addition, they allow computation of the irrigation water use at both maximum yield and maximum profit, and by difference, the potential savings. Results from this study and case studies from others will be presented to provide estimates of the potential for water conservation using precision irrigation.